A front vehicle body forms an engine compartment located in the front along the length of a vehicle. The front vehicle body includes a front end module forming a front part of the engine compartment and equipped with a cooling module and a head lamp, etc. A front fender apron member is provided at left and right sides of the engine compartment and forms a space for wheels as well as a suspension system. A dashboard is provided between front seats of the vehicle and the engine compartment. The front vehicle body further includes a front side member extending along the length of the vehicle in a lower part of the engine compartment and disposed from the left to right sides in the width of the vehicle, and a subframe supporting a suspension system, an engine that is disposed in the engine compartment, a transmission, and so on.
FIG. 1 illustrates a conventional vehicle structure described above in which, hCOG represents the center of mass of a vehicle, Mcabin represents a moment of inertia of a vehicle body with the center of mass of the vehicle as a center, LFR_SUSP represents a distance from a front suspension to the center of gravity, LRR_SUSP represents a distance from the center of mass to a rear suspension, FFR_SUSP represents an external force applying on the front suspension, FRR_SUSP represents an external force applying on the rear suspension, Fs/mbr represents an external force applied to a front side member when the vehicle collides, Ff/a_upr represents an external force applied to a fender apron upper member when the vehicle collides.
When the vehicle collides with a front obstacle, since the front side member extends farther than the fender apron upper member along the length direction of the vehicle, an impact is applied to primarily on the front side member as the external force Fs/mbr and then applied to the fender apron upper member as the external force Ff/a_upr.
The external impact Fs/mbr applied to the front side member generates the moment Mcabin=Fs/mbr*hCOG which rotates the vehicle body in a counterclockwise direction with the center of mass hCOG, and the external force FFR_SUSP, which presses the vehicle body from the top to the bottom in a height direction of the vehicle is applied on the front suspension by the moment Mcabin. The external force FFR_SUSP, which lifts up the vehicle body from the bottom to the top along the height of the vehicle, is applied on the rear suspension.
Additionally, the above-described moment Mcabin causes sinking, in which a front side of the vehicle and a vibration measuring part D subside to the ground G, as shown with the arrow in FIG. 1. Such a sinking phenomenon deteriorates safety of a passenger, for example, by deteriorating airbag performance when the vehicle collides with the obstacle.
Therefore, it is necessary to improve the vehicle structure in order to enhance the safety of the passenger by reducing the sinking amount when a vehicle collision occurs.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the inventive concept, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.